TIN clipping algorithm is one of the basic algorithms for digital mining design of open-pit coal mine based on TIN model. In this paper, a precise TIN clipping algorithm for digital mining design of open-pit coal mine is proposed. Based on the constructed grid index of the clipped TIN and the clipping polygon, the clipping polygon is embedded into the clipped TIN by interpolating the vertex elevation of the clipping polygon and calculating its intersections with the clipped TIN. Then, according to the reconstructed topology of the TIN triangles located inside (outside) the clipping polygon, generate the boundary of those two triangles set, and construct the TIN between the boundaries using the one-time edge-prior CDT growth algorithm, thus , achieve the precise TIN clipping keeping the clipped TIN’s local detail features. The experiment results show that the algorithm proposed in this paper is efficient, stable in performance, and it has been applied to the digital mining design of the open-pit coal mine.